The present invention relates generally to data communication. More particularly, the invention relates to a technique for data recovery and error concealment using data hiding.
It is well known that media data can be vulnerable to channel errors, to different degrees, when they are transmitted through an imperfect communication channel, especially when the data is compressed. That is, during transmission, sometimes chunks of data are lost through transmission error.
Conventional methods often rely on the relationship between the corrupted data block and neighborhood blocks to conceal the error effect. This is done at the receiver end, where the values of missing data are estimated using the corrupted blocks neighborhood data values. One disadvantage of this method lies in its incapability to comprehend the actual content of the lost data block, especially when the lost data block size is relatively large or continuous, or when a perceptible quality, such as the luminance distance, between the lost data block and its neighbor blocks is large. In this scenario, perceptible artifacts can often be detected after the recovery.
If, however, some amount of knowledge of the lost block content is given, the data restoration may give better results. Knowledge of the average luminance and the motion vector of a video data block, for example, would make data restoration of a video stream more successful.
The present invention provides a system and method that uses data hiding techniques to recover or repair the missing or damaged data chunks, such as the missing strip of data shown in FIG. 1. The technique involves hiding a content representative amount of information generated or extracted from each data block into another block of the image. The hidden content serves as an abstract or signature for the block it was generated or extracted from.
When data recovery is needed, the content, such as the average luminance, of the lost block can be extracted from the hidden data stream in the non-corrupted blocks and therefore used to best conceal the error effect. Applications of the invention include recovering frame dropping and picture error in video, recovering missing data chunks or scan lines in image data, repairing lost data in faxed documents and reducing error in audio and other data intensive communications.
For a more complete understanding of the invention, its objects and advantages, refer to the following specification and to the accompanying drawings.